The present invention relates to a cell module, particularly, to a cell module having a cell group with a plurality of cells connected to each other.
Generally, a power source device has a cell module with many cells connected each other to obtain high power, and if necessary, more cell modules are further combined. For example, a power source device for vehicles adopts to combine many cell modules and mounts them on the vehicles.
As an example described above, a technique is disclosed in a Japanese laid open patent publication No. 1998-270095, in which many cell modules with cells connected each other are attached to an end plate including a bus bar for conducting many cells connected each other, the end plate is fixed to a holder case, the holder case is attached to an outside case, and the outside case to vehicles.
On the other hand, a lithium ion battery is used as cells constituting the cell module, for example. When reached an abnormal state such as over-discharge or the like in the lithium ion battery, gas occurs from a power generation element such as an activated substance, electrolyte fluid or the like. In the case of closed type, the occurred gas raises an internal pressure of the cell. If the internal pressure continues to rise up, the cell finally goes to be burst.
Therefore, a gas discharge mechanism for discharging the gas is provided and when the internal pressure is reached to a predetermined value, the gas discharge mechanism starts discharging the generated gas. As the generated gas in the power generation element becomes high temperature and high pressure, it is not suitable to discharge the gas from the cell module without appropriate treating. Therefore, a new mechanism is required for discharging the gas to the outside of the vehicles safely.
As such an example, a technique is disclosed in a Japanese laid open patent publication No. 2005-322434 in which the gas is diffused and the temperature and pressure are fallen down by accommodating the cell in the case, and disposing a gas opening portion of the cell and a through hole for discharging the gas to the outside of the case so as not to oppose each other.